Tool adapter with rotary impact



Jan. 21, 1958 D. c. 130E 2,820,536

TOOL ADAPTER WITHROTARY IMPACT 7 Filed Jan. 26, 1953 IINVENTQJR.

BY All/[Z C B0 AYTORMEKS United States Patent TOOL ADAPTER WITH ROTARY IMPACT Daniel C. Boe, Minneapolis, Minn. Application January 26, 1953, Serial No. 333,082

1 Claim. or. 192-305 This invention relates to a tool holder and more par ticularly to a device for holding a variety of rotary tool elements and for imparting intermittent shock or impact thereto during operation.

It is an important object of the invention to provide for a tool adapter which will be mountable upon the rotary shaft of a power source such as in the chuck of an electric drill and which will impart intermittent torque shocks to an article such as a nut being driven home on a bolt.

A number of prior art devices have been proposed for imparting rotary movement to such tools as socket wrenches and so forth. When a certain predetermined degree of resistance to rotary driving force has been reached, then the device will slip under some sort of frictional resistance, but during slippage will create intermittent bumps or shocks which will serve to further rotate or draw home the article which is being turned. By way of example, head bolts on the motor of an automobile can be given an additional turn or fraction of a turn by use of an impact type wrench without the expenditure of nearly the amount of power which it would take to further draw up the head bolt by means of steady pressure such as exerted by and upon a conventional manual wrench.

Some of the prior art impact clutches have their shock elements disposed between planes normal to the axis of rotation thereof. Such as arrangement causes a reciprocating or up and down impact in .the same direction as the axis of rotation. Although the result may be such as to assist in driving home such articles as nuts and bolts, nevertheless, the amount of useful work obtained therefrom is less than where the shock or impact is imparted tangentially to a radius outwardly from the axis of rotation. Furthermore, the entire device together with the mechanism which imparts the rotation, will be subjected to an unnecessarily excessive amount of wear for the amount of useful work done. Where the endwise shock is employed in manually held instruments, the rapid impact is transmitted to the hand of the operator and sometimes causes physical discomfort.

Other impact clutches with which I am familiar have ball elements rolling in circular spaced races, the spaced races having offsets for engaging the balls and the balls themselves being projected outwardly by centrifugal force. Such arrangement is objectionable first of all because of the unbalanced relation of the elements causing the impact. In other words, there will be a lateral impact imparted to the driving and the driven shafts as well as a tangential force. This causes excessive wear upon the parts within the device as well as strain and unnecessary friction upon the driving mechanism. Furthermore, a small amount of gummy substance or grit in contact with the surface of the impact balls may prevent their proper positioning by centrifugal force. An impact clutch device of one size may have balls of a sufficient weight and radial position to cause the required de- 2,820,536 Patented Jan. 21, 8

gree of impact, whereas a smaller prototype of the same device may not function at all, the size and weight of the balls being insulficient for the speed and radial positioning to cause them to throw out by centrifugal action.

It is therefore another object of my invention to provide for a tool adapter having an impact clutch in which the impact elements are positively balanced so that discontinuous shock and impact will be imparted tangentially from the driving shaft to the driven shaft without of itself causing end thrust or lateral thrust upon or between the elements of the device.

It is a further object of the invention to preserve a radial balanced relation in a resilient impact clutch even in the presence of frictional drag such as caused by gummy substance or dirt particles, the balanced radial relation eliminating undue wear which would result if the shock and impact were unbalanced instead of even and balanced as in my device.

These and other objects and advantages of my invention will more fully appear from the following description made in connection with the accompanying drawings wherein like reference characters refer to similar parts throughout the several views and in which:

Fig. 1 is a vertical sectional view of my impact clutch taken on the axial line thereof, certain parts being shown in full line;

Fig. 2 is a cross sectional view of the device taken on the line 2-2 of Fig. 1, the impact balls therein being shown in full line;

Fig. 3 is a vertical sectional view of a modified form of my invention having a single pair of impact balls and a sleeve bearing structure, certain parts thereof being shown in full line; and

Fig. 4 is a cross sectional view of a further modified form of my invention in which the radial chambers comprise a set of three, each having an impact ball in full line at the outer end and compression springs converging at a common point.

Referring now more particularly to the drawing, my device comprises a shaft 10 which terminates outwardly in an axial fastener 11 such as a square shank having a resilient detent 12 for engaging socket wrenches and the like. The axial fastener 11 may be male or female and adapted to engage a large variety of rotary tool elements. The shaft 10 has at its other end one or more sets of cylindrical chambers 13 which are radially mounted with respect to the axis denoted by center line 14 longitudinally of the shaft 10 and of my device in general. Each of the cylindrical chamber sets may comprise a plurality of radial cylinders which may be two in number and axially aligned as in Fig. l or may be more than two and symmetrically spaced as in Fig. 4. Where the radial cylinders are oppositely disposed a continuous diametrical chamber is formed as illustrated by either of the cylinders 13 in Fig. 1. It is important that each of the radial portions of the cylindrical chambers emanate from a common point on the axis 14 of the shaft. In the particular form shown in Fig. 1, I have illustrated two diametrically opposed cylinder chambers each lying directly in the axis 14 of shaft 10 and also lying in the same plane for a reason which will be discussed later. Impact elements such as hardened ball bearings 15 are slidably positioned at the outer ends of the radial cylinder chambers 13 and have interposed therebetween a resilient means such as compression spring 16 for urging the impact members 15 divergently with equal and opposite force. The extreme inner end of the shaft 10 may terminate in a reduced axial stub 17 for journaling purposes.

Surrounding the shaft 10 at its medial and inner portions isa casing 18 having a longitudinal bore 19 and being mounted for rotation on the same axis 14 as the shaft 10. A bearing element such as the ball bearing as sembly 2% may be positioned within the longitudinal bore 19 and also axially disposed with respect to axis 14. The reduced stub portion 17 of the shaft may bef'otatably secured within the bearing assembly 2'0. A cap member 21 having'an axial opening 22 and holding a bearing assembly 23 is threadably mounted over the open end of the longitudinal cylindrical bore 19 and a medialeportion of shaft 10 is journaled within the bearing assembly 23. The outer end of theca'sing 18 terminates in an axial fastener 18a which is oppositely disposed to the axial fastener 11 and may be a male or female member for securing to a tool element or to a source of power. The axial fastening elements 11 and 18a may be'ihterchange'd, the device working equally well whether driven'from one end or the other. A recess 24 is formed inthe inner cylindrical wall of bore 19, one for each radial cylindrical chamber within a set thereof. In the embodiment shown in'Figs. land2, the recessed portions 24 are two in number and are diametrically opposed so as to match with the diametrically positioned impact members 15. Where there is a greater number of radial cylindrical chambers as indicated by the numeral 25 in Fig. 4, then the recesses 26 will be similarly disposed in symmetrical relation and of the same number as the number of radial cylindrical chambers. The embodiment of Fig. 4 shows three such symmetrical chambers and recesses. It is understood, of course, that a greater number may be employed, always maintaining equal spacing and having the same number of recesses as cylindrical bores. The inner ends of compression springs 16a may be positioned differentially upon ball b.

Referring now to Fig. 3, an alternate form is there shown in which the entire device is reduced to its simplest form. In this case the shaft 10a has a similar axial fastener 11a but has but one diametrical cylindrical chamber 27. The ball bearing assemblies are replaced by sleeve bushing members '28 and 29, the bushing 28 being threadably disposed within the outer end of bore 19a of the casing 30. A single straight compression spring 31 isshown in Fig. 3 and the axial fastener opposed to fastener 11a is shown in the form *of a male member 32. The cylindrical bore 19a has diametrically opposed recesses 33 which are similar to those formed in the cylindrical bore 19 of Fig. l. The reduced inner end 34 of shaft 10a is journaled within the bushing 29. The impact members comprise ball bearings 15a having interposed therebetween a compression spring 16a similar to the embodiment shown in Fig; 1.

Operation In the use of m tool adapter, the axial fastener or the casing "element is secured to a source of rotary power and the aligned axial fastener 11 is secured to a tool such as a socket wrench. The device is then applied to such article as a bolthe'ad and then rotary movement applied from the source of power. When the bolt has been tightened to the point where the impact balls 15 begin to yield, then the rotation 'of shaft 10 will cease, while the casing member 18 'continuesto revolve at a high rate of speed. The recesses 24'will then successively contact all of the impact balls 15 simultaneously, first in the relation shown in Fig. 1, th'en'in opposed relation with the balls reversed with respect to the recesses. Each impact will cause asligh't tightening movement to the bolted head which can be visually observed by slow rotation of the socket wrench. when the rench ceases to turn further, thebolt will have been driven home to its fullest extent. The period of time required for the impact operation is usually but a few seconds.

when "emp1 ying the "alternate "form shown in Fig. 3 the same results are obtained -with a single pair of opposed impact ball elements. With the arrangement shown in Fig. 4 the impacting is also simultaneous, the set of impact balls in this case being three in number.

It will be observed that the shock or impact which is imparted to the tool holding shaft is tangential in nature and is applied diametrically in equal and opposite directions. The recesses are preferably parabolic in cross section so that the impact ball can more quickly enter therein before the impact occurs. If the rotation of the device is always in one direction, then the recess may have a sloping side where the impact ball first enters it, always, however, maintaining the impact surfaces exactly diametrically opposed. The interposed spring element causes equal pressure to be exerted to the opposed impact members in order to further insure the balanced quality of the device in operation. Since the tangential impact lies in the same plane normal to the axis of operation, there will be no compound forces tending to cause lateral movement of the shaft element with respect to the sheath or casing element. As a consequence, the relatively moving parts will not be subject to more than normal frictional Wear and vibration of the rapid series of impacts 'Will be held to a minimum with respect to the source of power which rotates the tool adapter. Much larger units can thus be easily handled 'manually and over a long period of time "without physical discomfort to the operator. Since the adapter can be quickly disassembled various strengths of springs 16 may be kept on hand and can be interchanged at will so as to achieve a varying degree of impact depending upon the purpose to which the device is put. Thus, where a large size socket wrench is used on the axial fastener 11, a stronger spring 16 may be employed. On the other hand, if a series of small nuts or bolts are to be run, a smaller and lighter spring 16 can be'employed. If the device is used interchangeably between a number of different sized articles it may be preferred to use an intermediate sized spring which will serve a range of sizes of nuts or bolts.

It will be noted that in the embodiment shown in Fig. 1 a plurality of radial chambers are employed which will serve to distribute the impact upon more than one set of impact elements at one time. The recess 24 may be conveniently formed as a single groove to accommodate the plurality of impact elements. It will be further noted that the device can be made flexible by not only interchanging the sizes and strengths of spring 16 but one or more of the springs may be entirely omitted so as to leave at least one set in working condition.

Although my device can easily work end for end, I prefer to have the shaft 10 secured to the tool and the fastener 18a of the casing 18 secured to the source of rotative power. The reason for thelatter preference is that the activity of spring 16will not be compounded by centrifugal force applied to balls 15 after slippage between the casing and'shaft begins. The casing 18 will "continue to revolve at high speed but the shaft It) will be virtually stopped. I'prefer to avoid the centrifugal action because of its unreliability in the 'presenceof dirt or gummy material. My spring members, on the other hand, furnish a completely reliable means for applying simultaneous impact and for-preventing any of the impact ball members from bearing more than their share of the impact stress.

It may thus be seen that lhavedevi'sed a simple mechanism for applying with a minimum of vibration, a maximum of torque with clutch impact while at the same time preventing excessive wear and breakage within the device itself.

It will, of course, be understood that various changes may be made in theform, details, arrangement and proportions of the parts without departing from the scope of my invention.

What I claim is: g

A tool adapter for imparting torque withvibraticnal impact, comprising a shaft terminating outwardly in an axial tool holder, cylindrical chamber means formed laterally of the axis of and in said shaft, a casing with a longitudinal bore mounted fc balanced rotation on the same axis with said shaft and interfitting in overlapping rotatable relation therewith, said casing terminating outwardly and oppositely to said tool holder in an axial fastener adapted to be rotatably secured to a drive member such as an electrically powered chuck, retaining means providing thrust bearing surfaces between said casing and said shaft for maintaining the same against relative axial shifting, a recess for each outwardly terminating end of the cylindrical chamber means in the inner circumference of said casing, said recesses being of fixed equal depth, an impact ball element disposed slidably within each outer terminus of said chamber means and normally aligned to enter and strike the walls of said recesses simultaneously and in balanced relation, and a compression spring means disposed within the cylindrical chamber means exerting outward balanced force upon each of said impact elements to urge them outwardly against said inner casing circumference and for exerting balanced outward pressure and impact force between said shaft and said casing during relative rotation thereof, said impact elements during said relative rotation having a lesser speed of rotation than that of said casing.

References Cited in the file of this patent UNITED STATES PATENTS 1,671,521 Fisher May 21, 1928 2,164,870 De Salardi July 4, 1939 2,373,812 Coop Apr. 17, 1945 2,544,809 Stanley Mar. 13, 1951 FOREIGN PATENTS 15,816 Great Britain Feb. 3, 1916 

